Aspects of the present disclosure relate generally to fiber optic cables. More specifically, some aspects of the present disclosure relate to fiber optic cables supporting ribbons of optical fibers, such as for device-interconnection applications in data centers and the like.
Demand for increasing bandwidth of data communication systems has been addressed by various means, such as using wavelength division multiplexing (WDM). However, costs of transmitters and optical devices for WDM to combine signals at the transmitter and separate them back out at the receiver may be prohibitive for some cost-sensitive applications. Another approach to increasing bandwidth has been increasing transmitter speed from 1 gigabits per second (Gbps) to 10 Gbps, and recently to 25 Gbps, with low-cost vertical-cavity surface-emitting lasers (VCSELs). However, VCSEL technology may have reached a maximum speed limit of 25 Gbps per optical channel and there is demand for 40 Gbps and 100 Gbps systems.
Yet another low-cost solution for increasing bandwidth is use of VCSELs coupled with parallel-optic transmissions, where a signal may be broken down into sub-signals, parsed, communicated via into separate optical fibers for transmission in parallel with one another, and then reconfigured upon receipt. Standard schemes for parallel-optic transmissions are described in IEEE 802.3-2005: Information Technology-Telecommunications information And Exchange Between Systems—LAN/MAN—Specific Requirements—Part 3.
Two types of fiber optic cables used with parallel-optic transmission systems include loose fiber cables and fiber optic ribbon cables. Ribbon cables offer advantages over loose fiber cables, such as ordered arrangements of the optical fibers, facilitating efficient and accurate attachment of a connector to the ribbons. However, traditional ribbon cables may exhibit strong preferential bending and/or are inflexible, such as due to the presence of a buffer tube protecting the ribbon stack, arrangements of rigid strength members, and/or a generally long lay-length of the ribbon stack (i.e. distance for one full twist of the stack, which is typically wound within such a cable to reduce stresses on the stack when the cable bends). As such, loose fiber cables are currently more-preferred in the industry because they are generally smaller and more flexible. A need exists for a ribbon cable that is flexible and has little or no bend preference, similar to a loose fiber cable, such as for use interconnecting optical devices used with parallel-optic transmission systems.